1. Field of the Invention.
This invention relates generally to computer hardware and software, and more particularly to caching information on a network.
2. Description of the Related Art.
Information such as files, documents, pictures, sound clips, video, etc. are stored electronically on computers. To share such information among multiple computer users, a network may be utilized wherein multiple computers are connected and may communicate with each other. The Internet is a large network made up of more than 65 million computers in more than 100 countries covering commercial, academic and government endeavors. Information is disseminated across the Internet from one computer referred to as a server in the form of web pages that may be viewed using web browser applications executing on a user's computer (referred to as a client).
Web pages may be static documents consisting of hyper text markup language (HTML) tags or codes, embedded in the text. HTML defines the page layout, fonts and graphic elements as well as the hypertext links to other documents available on the network. Each link contains the uniform resource locator (URL), which provides the location or address, of a web page residing on the same server or any server worldwide. Alternatively, web pages may be created dynamically by the server or client. Such dynamic creation may be in accordance with a client's preferences or requests.
Typically, a client using a web browser requests a web page by entering or selecting a link. The request is delivered to the server at the specified location. Thereafter, the server creates the web page if necessary, and responds to the client with the static or dynamic web page. Alternatively, the request may specify an applet (a small application that executes on a client) or various objects. The server forwards the applet or objects to the client who then executes the applet or utilizes the objects to dynamically create and display the web page on the browser.
One problem with disseminating information across the Internet is the transmission rare of the information. If a client is connected to the Internet using a modem and an analog telephone line, the transmission rate depends on the speed of the modem (e.g., a 56 Kbps modern, the current top speed, or older 28.8 Kbps modems). Alternatively, faster transmission means may be utilized such as a Digital Subscriber Line (DSL), Integrated Services Digital Network (ISDN), cable modem, T1 line, etc. With any transmission means, the user must wait while the information is transmitted across the Internet. Once the information has been received, it is processed and then displayed. Accordingly, the speed with which a user may view a web page depends on the speed with which the information may be retrieved by the web browser.
To speed up the display speed of a web page, a web browser may store previously requested and viewed web pages in a browser cache on the client. A browser cache is a folder on the local client disk that holds popular web pages. The first time a web page is requested and retrieved, the page is stored in the browser cache where it can be retrieved and displayed by the browser more quickly. Thereafter, caching servers update the pages in the folder with the latest version from the Internet.
However, web pages are only stored in browser cache when a user has specifically requested and retrieved the web page from the server on a per page basis. There is no mechanism to allow web pages that are likely to be viewed in the future to be retrieved prior to the user actually requesting the web page. Consequently, although cache may expedite the time needed to display a web page, a user must first request the page and then wait to retrieve it.